My landscaper has just completed a garden that includes a patio of polished limestone from Global Stone. The clients want the paving sealed.
The Global Stone brochure recommends waiting 6 weeks before sealing new paving. If the reason for sealing is to help keep the stone clean, how do you do this in the period between laying and sealing? Or do you cross your fingers and budget to clean the stone if you need to?
The installation is showing signs of efflorescence. I don't think we can seal until this has stopped, but it could take some time (atleast we didn't seal it in). At the moment the clients are being very understanding, but what do we do if it goes on for months and the stone starts staining?
I would love to hear what others do in this situation, and any advice would be much appreciated.
Pressure wash it the day before sealing. This should also clear minor efflorescence and get the stone clean and ready for sealing. If the efforescence is more significant you will probably have to wait longer.
personaly i would wait until it stops and then seal the patio, i have only ever had this happen once, the slabs i used were modak indian stone but ot only happened in the rear part of the garden where i had laid weed suppressing membrane under the patio, the front garden didnt have any weed membrane and didnt get any problem.
There is a lot of mis-information flying around about sealing. In my experience all sawn paving, whether sandstone or limestone should be sealed. When a natural stone is sawn the pores of the stone are opened up which make it much more porous than for example a riven sandstone or limestone. The only sawn products I would not reccomend sealing are some of the ultra hard imported sawn sandstones. The reason for this is because they are so dense that the sealant sits on the surface and gives a really awful sheen which completely ruins the character of the stone.
We always reccomend to our clients that if possible to seal the stone before it is installed. The reason for this is that stone needs to be bone dry before it can be sealed and we all know what the British weather is like. I have known clients having to wait weeks to seal stone due to bad weather. Somebody earlier mentioned waiting for the effo to dissapear before sealing, this is a valid point and was the same advice we used to give to our customers but then we found a sealant called drytreat which prevents any effo from coming through the stone.
In response to the initial post my advice would be not to worry, natural stone is hard and robust and it will be ok (you will be able to remove any stains, especially from limestone). Wait a few weeks until any effo has come through. Wait for a few hot days and give it a good clean, let it dry for 24 hours and seal it. At the end of the day it sounds like you have got your clients best interests at heart, so hopefully they should understand.
All the best
Thank you everyone for your replies.
I really like the sound of Dry Treat. Being able to seal without having to wait for the efflorescence to stop would be ideal. Also, we don't want to wait too long as this will increase the chance of staining and we have a hose-pipe ban, so pressure-washing is a no-no!
I assume the recommended 6-week wait is to allow the construction to dry out, although it seems quite a long time. Do you all wait this long or do you just wait for a few nice days?
We always reccomend that our clients seal it before it goes down (not always possibble) or seal it asap after installation.
Dry treat offer a 15 year guarantee if the sealant is applied by a drytreat trained installer. the best thing is Drytreat will send somebody to your project who can train you on the job while you are sealing your project. You are then a registered drytreat installer and can offer a 15 year guarantee to your clients on sealing. Drytreat is approx £10 per litre more than lithofin but when you consider that lithofin needs to be re-applied every 3 years, the extra tenner is a small price to pay
The following is an excerpt from Marshalls standard advice about sealing paving -
"The application of propriety sealing agents to paved surfaces is becoming increasingly common. The benefits gained from sealants are generally considered to be ease of cleaning and maintenance of the surface and the retention of jointing sand in flexible construction.
The resulting impact of the sealant on the paving performance and appearance must, however, be given careful consideration. In particular, the following issues should be noted.
The sealant must only be applied in reasonable climatic conditions, to a surface which is dry and free from dust, surface deposits or efflorescence. Any such deposits which are not removed will become trapped beneath the sealant.
The sealant should not adversely affect the slip/skid resistance value of the surfacing product. Areas which receive frequent or heavy trafficking may require the sealant to be reapplied periodically to maintain performance. The resulting visual effect of the sealant should be judged on a small trial area prior to application.
Some sealants may give a sheen to the surface or create the impression that the paving is wet. The sealing of internal paving may be beneficial to reduce dust generation and help with cleaning. Adequate ventilation of the area to be sealed is important.
Water based acrylic sealants are preferable to solvent based products with the manufacturers’ instructions being carefully followed at all times."
Of course, some products now take this out of the equation